The methods of cleaning of textile substrates may be generally placed into three categories. The first category involves the immersion of the textile into a cleaning solvent followed by agitation and removal of soiled solvent. In this case, water is the preferred solvent, provided that the fiber and/or textile substrate is stable to it. Typically, the additives used to facilitate soil removal by the solvent are surfactants, ionic chelators, and pH adjusters. Other minor ingredients are generally included to enhance the cleaning process. These include fragrances, bleaches, optical brighteners, and anti-resoil ingredients. For example, U.S. Pat. Nos. 5,786,317; 6,010,539; and 5,714,449 to Donker, et al., describe a non-aqueous liquid cleaning composition containing solid particles suspended by the use of hydrophobically modified silica particles. This composition is designed for liquid detergent concentrates for washing machine applications and the particles are active bleaching agents. If the textile is small, this process generally uses standard washing machines or dry cleaning machines to clean the textile. If the textile is large or physically affixed to an object, this process uses portable liquid applicators and vacuum retrieval of the soiled fluid. This method, often referred to as “hot water extraction,” applies a substantial amount of water based cleaning solution to the textiles, such as a carpet or upholstery, and uses vacuum extraction to partially remove the soil and surfactant laden cleaning solution. This process typically leaves a residual surfactant on a carpet that attracts dirt to its surface and provides a wet textile that can take many hours to completely dry. The water in the composition is known to cause rust stains if it comes into contact with iron-containing objects, as well as, to provide enhanced growing conditions for mold and other microorganisms. These deficiencies are substantially overcome by powdered cleaning compositions.
The second general category of methods for cleaning textiles involves applying foam-containing solvents and surfactants to the textile followed by agitation with a brush or damp mop. Typically, the applied foam collapses after contact with the textile, and the spots and soil become less visible. While the appearance on the surface of the textile, such as a carpet, is improved, very little dirt or surfactant is actually removed. The main advantages of this method are the ability to use household tools and equipment and the rapid cleaning cycle. Canadian Patent No. 985113, assigned to Unilever Limited, shows a variation on this wherein a non-scrub foam, which contains soil retardant particles, is applied to the carpet. These soil retardant particles remain as a residue on the carpet after the other components of the foam are removed by vacuuming. While this method can be used to improve the appearance of a carpet, it is not an effective method of removing dirt. Furthermore, it leaves a substantial amount of residue on the carpet.
The third general category of methods of cleaning textiles involves applying a solid composition that contains a solvent and a cleaning surfactant to the textile followed by agitation. Typically, the solvent is allowed to evaporate and the soiled particles are retrieved with a vacuum cleaner or removed by brushing. Powdered cleaning compositions, or other dry-type cleaning compositions, generally contain, in addition to a liquid component and surfactant component, any of a rather wide variety of both natural and synthetic solid particulate materials. Natural solid particulate materials include, for example, buckwheat flour (see U.S. Pat. No. 2,165,586 to Studer), wood flour, and diatomaceous earth of specific particle size and low bulk density (see U.S. Pat. No. 3,418,243 to Hoxie). Synthetic solid particulate materials include, for example, polymeric materials such as polyurethanes, polystyrenes and phenolformaldehyde resin particles, as disclosed, for example, in French Patent No. 2,015,972. Several examples of powdered cleaning compositions are discussed below.
U.S. Pat. No. 4,013,594 to Froehlich et al. discloses a powdered cleaning composition that contains, as a major component, solid polymeric urea-formaldehyde particles and a solvent component which may be chosen from water, high boiling hydrocarbon or chlorinated hydrocarbon solvents, aliphatic alcohols and mixtures of such compounds.
U.S. Pat. No. 4,108,800 to Froehlich discloses a semi-dry powdered cleaning composition which further contains polyethylene glycol as an aid to prevent the adherence of fine particles to the fibers being cleaned. This reference further describes the visual problem of “frosting” that occurs when small particles are formed from particle to particle attrition as a result of agitation, such as by brushing.
U.S. Pat. No. 4,194,993 to Deal discloses a process for making a powdered cleaning composition which includes the steps of polymerizing urea and formaldehyde in acidic solution to form particles of a desired size, centrifuging the particles, blending polyethyleneoxide into the polymer, and spraying a fine mist of detergent solution onto the polymer mass as it is blended.
U.S. Pat. No. 4,434,067 to Malone et al. discloses a powdered cleaning composition that contains, in addition to a particulate polymeric material such as urea formaldehyde, an inorganic salt adjuvant and an aqueous or organic fluid component. The Examples and the Tables illustrate that the maximum content of fluid in these powdered cleaning compositions as 40% of the total composition. They further describe the formation of pastes and non-flowable solids when the liquid level or the inorganic salt adjuvant component represents too high a proportion of the total composition.
U.S. Pat. No. 4,802,997 to Fox et al. discloses a cleaning composition that contains a hydrogel polymer that acts as a carrier for a treatment liquid. The composition may be sprinkled on a textile surface and is capable of ejecting the treatment liquid under mechanical pressure or brushing. The hydrogel polymer is then capable of reabsorbing the treatment liquid when the mechanical pressure or brushing is removed. The hydrogel polymers preferably have a particle size distribution wherein the majority of the particles are greater than 250 microns. The cleaning composition may also include flow aids, such as chalk or cellulose materials, to improve flow characteristics of the composition.
U.S. Pat. No. 4,659,494 to Soldanski et al. describes a cellulose powder containing dry carpet cleaner with reduced dusting, particularly if the carpet cleaner did not contain added surfactant.
U.S. Pat. No. 4,908,149 to Moore et al. discloses improved carpet cleaning compositions that include acid dye stain blocker additives. These compositions range from particle-free solutions to dry-type powders with a minimum of 30% solid particle content.
U.S. Pat. No. 4,873,000 to Weller discloses a powdered freshening and deodorizing composition for carpets. The composition contains inorganic salts in combination with aluminum silicate clay to improve vacuum retrieval. The composition further contains a maximum of 4% liquid comprised of fragrance and organic agglomerating agent.
EP 1,063,282 B1 to Lang et al. discloses a cellulose-based, porous, particle gel carpet cleaning composition in combination with water and alcohol. This composition remains in the gel state even in the presence of an 80% water and alcohol mixture.
U.S. Pat. No. 5,783,543 to Fleckenstein discloses a scatterable powdered cleaning composition incorporating viscose sponge flakes from 3 to 10 mm in length. The improved composition results in less disruption of the carpet fibers due to the brushing process.
EP 1184449 to Gagliardi et al. describes a solid cleaning composition with low water content that is particularly useful for cleaning wet spills. The composition incorporates water swellable polymers and anhydrous salts to absorb liquid and turn wet spills into powders that can be removed by vacuum cleaners. The cleaning of wet spills by conventional powdered cleaning agents is problematic due to the potential to form pastes that are not vacuum retrievable.
U.S. Pat. No. 6,569,210 to Chao et al. describes a novel fabric cleaning method whereby soils are treated with a particulating chemical, such as a colorless sulfonated dye site blocker, to generate particles that are then removed by gas jet interaction.
U.S. Pat. No. 6,010,539 to Pesco discloses a modern example of cleaning compositions for hot water extraction systems. This composition is free of organic solvents and contains water, detergent builders (such as sodium tripolyphosphate), EDTA, non-ionic surfactants, stain soluble resist polymers (such as methacrylic acid salts) and a fluorosurfactant.
Thus, as is illustrated by the previous efforts of others, the use of solid cleaning agents for carpet or upholstery has been recognized as the superior method of cleaning. Its low water content allows both for rapid drying and safe cleaning of even expensive wool carpets. The hand application (i.e. sprinkling and spraying methods) and brushing followed by retrieval using the household vacuum cleaner requires no specialized machinery. The particles absorb both sticky soils and residual surfactants so that the textile remains cleaner much longer. In addition, solid cleaning agents have been established to effectively remove allergens, while not promoting the growth of micro-organisms.
There are, however, limitations to the use of solid cleaning agents. Powdered cleaning compositions contain a maximum level of water to aide in cleaning efficacy. At this level of water content, powdered cleaning compositions are not free-flowing. The damp powder clumps and cannot be sifted through small holes for use by the consumer.
The solid cleaning agents may be characterized by the classical Critical Pigment Volume (CPV) effect. The CPV is also known as the oil value, which may be determined by ASTM D281 and which is described, for example, in U.S. Pat. No. 3,956,162 to Lautenberger. To remain a flowable powder, the maximum liquid content is restricted to below the CPV. For particles of a certain shape, the CPV is the volume between particles filled with air. As the air is displaced by a fluid, the flow properties of the powder are reduced until, at the CPV, all the particles are surrounded by liquid. At that point, the mass has the consistency of putty. If more fluid is added, the putty gradually thins until a paint-like dispersion is generated. The practical problem of prior art solid cleaning compositions is that when wet spills are cleaned with powdered cleaning agents, it is possible to generate a paste consistency that, when brushed, does not remain free-flowing. This creates a spot that is very difficult to remove. In addition, if brushing occurs at the thick dispersion or paste stage the particle size can be mechanically reduced by particle to particle attrition. Particles having a particle size of less than about 5 microns are held very tightly by electrostatic force and are very difficult to remove by vacuum cleaners. This also leads to an observable residual spot of cleaner on the textile. Therefore, there is the need to provide a solid containing cleaning composition that avoids the practical side effects of the Critical Pigment Volume.
Additionally, in some instances, consumers have complained that the prior art powder cleaning compositions form clumps in the package and do not evenly disperse. These issues also detrimentally affect the manufacturing process because the composition may clog machine parts.
Thus, the need exists for an improved powder cleaning composition that addresses these issues. The composition of the present invention exhibits improved dispersing properties and less clumping, and therefore, provides a product that is easier to manufacture. At the same time, it allows for a higher water content to be present in the composition and still remain a free-flowing powder.
Attempts by others have included the incorporation of polyacrylic acid into cleaning formulations. For instance, US Patent Publication No. 2005/0261154 to Hammock discloses a surfactant-free cleaning composition that leaves a redeposition of particle coating on fibers containing polyacrylic acid sodium salt. US Patent Publication No. 2002/0090453 to Muthiah et al. discloses an article to which super absorbent particles are attached by a curable resin linkage which provides a reduction in particle loss. End-use applications include diapers and cleaning devices. WO 01/64179A1 to Jehn-Rendu et al. discloses a non-abrasive skin cleaning composition containing super absorbent polymers and polyacrylic acid. WO 00/78448 to Pierce teaches a method and device for cleaning liquid spills that is the blend of two super absorbent polymers that, when contacted with water, forms a unitary mass that is removable.
Canadian Patent Application No. 2107409 to Hughes et al. teaches modifying polyacrylic acid with free radical treatment to combine polymer chains to provide materials useful in cleaning and detergent formulations. U.S. Pat. No. 4,834,900 to Soldanski et al. discloses a two step process for cleaning stains from carpet using hydroxymethyl cellulose thickened liquid detergent followed by application of three times the original amount of a dry cellulose powder composition. U.S. Pat. No. 4,566,980 to Smith teaches a dry carpet cleaning composition containing inorganic carrier salts and agglomerating starch coated with polyethylene wax and polyacrylic acid.
It is thus an object of this invention to blend super absorbent particles with an absorbent particulate material to produce a free-flowing powdered cleaning composition that contains an even higher water content than the prior art powdered cleaning compositions. In addition, this composition, when used for wet spots or with normal pre-spray applications, greatly speeds the dry time and does not leave white spot residue. The super absorbent polymer particles may be pre-moistened before blending, yet they retain the ability to absorb up to 30 times their weight in water. Even when wet, the particles do not become sticky and retain the ability to be removed by vacuuming. This is in marked contrast to polyacrylate salts that form gels which glue particles to the fibers of the textile substrate.